<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    div {
      width: 100px;
      height: 100px;
      background: #000;
      animation: changeColor 2s;
    }

    @keyframes changeColor {
      /* from {
        background: #aaa;
      }
      to {
        background: red;
      } */
      0% {
        background: #000;
      }
      25% {
        background: #ff6600;
      }
      50% {
        background: blue;
      }
      100% {
        background: red;
      }

    }
  </style>
</head>
<body>
  <!-- 
    动画需要用户去创建动画规则
    @keyframes 动画名 {

    }

    animation: 创建的动画名 动画时间


  -->
  <div></div>
</body>
</html>